地铁隧道上方长距离并行基坑开挖的施工影响及变形控制

在深圳市桂庙路快速化改造工程施工过程中,前海下沉段需要长距离并行既有的地铁11号线隧道。这不可避免地会使下卧地铁隧道产生结构变形和附加受力,进而影响地铁隧道的运行安全。借助数值分析软件对基坑施工过程进行动态模拟,对比分析了不同工况下的坑顶土体放坡开挖、坑内土体开挖、主体结构施工等不同施工步序对下卧地铁隧道结构的受力和变形影响。在此基础上,提出了基坑分段开挖、控制基坑一次纵向开挖长度、前一段基坑开挖完毕后迅速施工底板等施工控制措施。现场监测数据验证了所提施工方法能有效控制下卧地铁隧道的变形。

Influence of Long Distance Parallel Foundation Pit Exca-vation on Subway Tunnel Construction and Deformation Control

In the reconstruction project of Guimiao Road in Shenzhen City,the sinking section runs parallel to metro Line 11 in a long distance,that will inevitably cause structural de-formation and additional stress to the underlying metro tunnel, affecting the safety of metro operation. In this paper,the pro-cess of foundation pit excavation is simulated by using numer-ical analysis software,the influences of foundation pit excava-tion in different working conditions on the deformation and stress of tunnel lining structure are compared accordingly,in-cluding steps of slope soil excavation,foundation pit excava-tion and construction of the main structure. On this basis,a se-ries of construction measures are proposed to control the de-formation of underlying tunnel,such as subsection excavation of the long foundation pit,longitudinal excavation length con-trol of each section and rapid floor construction after founda-tion pit excavation,etc. The field monitoring data have verified the proposed construction method in underlying tunnel defor-mation control.